<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <button>删除</button>
    <ul>
      <li>熊大</li>
      <li>熊二</li>
      <li>光头强</li>
    </ul>
    <script>
      // 1.获取元素
      var btn = document.querySelector("button");
      var ul = document.querySelector("ul");
      //2.删除元素 node.removeChild(child)
      //   ul.removeChild(ul.children[0]);
      btn.onclick = function () {
        if (ul.children.length == 0) {
          this.disabled = "true";
        } else {
          ul.removeChild(ul.children[0]);
        }
      };
    </script>
  </body>
</html>
